See-through sensing is important for many applications such as microwave imaging, biomicroscopy, medical imaging, through-the-wall imaging (TWI), infrastructure monitoring, and seismic imaging. In particular, the see-through sensing enables the visualization of the internal structure of the material and characterization of its physical properties. For example, in microwave imaging, the see-through sensing provides the structure of objects. In biomicroscopy, the see-through sensing allows to visualize the internal cell structure in three-dimensions. In TWI, the see-through sensing allows to compensate for the delay of the signal propagating through the wall.
For example, over the past two decades, there have been increased interests in terahertz (THz) sensing, in either a reflection or a transmission mode, due to the broad applications in gas sensing, moisture analysis, non-destructive evaluation, biomedical diagnosis, package inspection, and security screening. The THz sensing systems are able to inspect not only the top surface of the sample but also its internal structure, either a defect underneath the top layer or a multi-layer structure, due to its capability of penetrating a wide range of non-conducting materials.
However, the see-through sensing, such as THz sensing, suffers from complexity in image reconstruction of three-dimensional objects. In addition, to the complexity of computation, undesirable artifacts can diminish the quality of reconstructed images. Accordingly, there is a need for a system and a method for image reconstruction of a structure of a target object.